1. Field of the Invention
The present invention relates to a photoelectric conversion device including a semiconductor junction and a method for manufacturing the photoelectric conversion device.
2. Description of the Related Art
To deal with global environmental issues in recent years, the market for photoelectric conversion devices typified by solar cells such as residential photovoltaic systems has expanded. Bulk photoelectric conversion devices using single crystal silicon or polycrystalline silicon, which have high photoelectric conversion efficiency, have already been put into practical use. The photoelectric conversion devices using single crystal or polycrystalline silicon are manufactured by cutting wafers from large silicon ingots. However, since it takes a long time to manufacture large silicon ingots, the productivity is low, and since supply of raw materials of silicon itself is limited, the supply of silicon ingots is in short and cannot keep up with the expansion of the market.
As the shortage of raw materials of silicon becomes obvious as described above, thin-film photoelectric conversion devices using silicon thin films are attracting attention. In the thin-film photoelectric conversion devices, silicon thin films are formed over supporting substrates by a variety of chemical or physical growth methods. Therefore, it is said that the thin-film photoelectric conversion devices enable resource saving and cost reduction as compared with the bulk photoelectric conversion devices.
Development has been conducted on photoelectric conversion devices using amorphous silicon thin films, and development on photoelectric conversion devices using microcrystalline silicon thin films are also in progress in recent years. For example, a method for manufacturing a silicon thin film solar cell, in which microcrystalline silicon is formed as crystalline silicon by the control of the pulse modulation of a high-frequency electric power in a high-frequency plasma CVD method has been proposed (see, for example, Patent Document 1). Further, a method in which the deposition rate is increased by forming a silicon-based thin film photoelectric conversion layer using a crystalline substance with the controlled pressure in a reaction chamber by a low-temperature plasma CVD method has been proposed (see, for example, Patent Document 2).    Patent Document 1: Japanese Published Patent Application No. 2005-50905    Patent Document 2: Japanese Published Patent Application No. 2000-124489